METAL ACCUMULATION IN VARIOUS TISSUES OF Clarias gariepinus EXPOSED TO COPPER, ZINC, CADMIUM AND LEAD SINGLY AND IN MIXTURE

Accumulation of copper, zinc, cadmium and lead in gill, liver, spleen, kidney and muscle tissues of Clarias gariepinus was studied after exposing the fish to 5 ppm Cu, 5 ppm Zn, 1 ppm Cd, 1 ppm Pb and to the same concentrations of their mixture over 1, 7 and 15 days. Atomic absorption techniques were applied in determining tissue metal levels. Highest Cu and Zn accumulation was observed in liver and kidney tissues at all exposure periods whereas highest Cd and Pb accumulation was in gill and liver tissues. The lowest metal accumulation was observed in muscle tissue. Accumulation of these metals in the tissues studied increased compared to control when exposed singly. Tissue accumulation of metals, however, decreased when exposed to metals in mixture compared with single exposures to metals. It was concluded that exposure to these metals in mixture had an antagonistic effect on metal accumulation.